The apparatus herein relates, in general, to the type of apparatus disclosed in my prior U.S. Pat. Nos. 3,464,314 issued Sept. 2, 1969, 3,800,660 issued Apr. 2, 1974 and 3,910,159 issued Oct. 7, 1975. Such apparatus is generally concerned with machining curved surfaces upon large metal plates.
The invention of this present application is more specifically concerned with an apparatus for machining compound curves upon large, plate-like workpieces, i.e., curved surfaces which are both longitudinal and transverse of the workpiece.
By way of example of a workpiece, continuous casting molds used in the process of continuously casting steel into slab form, are generally of a rectangular in cross-section, open upper and lower ended box-like configuration where molten metal is poured into the open upper end, is chilled as it passes through the mold and comes out the bottom at least partially solidified. Such molds are lined with copper-like material plates. In certain types of such molds the plates are curved in transverse cross-section as well as curved from top to bottom. The vertical or longitudinal curvature may be formed to a radius of many feet, e.g., 20 to 40 feet, for example, and the transverse curvature, i.e., looking down, may be formed to a totally different radius of, for example, several feet. In any event the plate which may be perhaps a foot in width, three or four feet in height and two or so inches in thickness, may have a surface which is curved in transverse as well as longitudinal directions, with a considerable degree of accuracy required for such curvatures, such as in the order of two or three thousandths of an inch tolerance, depending upon the particular application.
With the above type of example, it can be seen that machining compound curves on such type plates with the relatively high accuracy required, is difficult to perform in conventional apparatus. Thus, the apparatus of the present invention is directed towards that type of machining operation.